Financial Derivatives (Schedule of Derivative Activity) (Details) - USD ($) $ in Thousands |
3 Months Ended | 12 Months Ended |
|---|---|---|
Mar. 31, 2020 |
Dec. 31, 2019 |
|
| Interest rate swaps | ||
| Derivative [Line Items] | ||
| Average Monthly Notional | $ 1,194,366 | $ 731,941 |
| TBA securities | ||
| Derivative [Line Items] | ||
| Average Monthly Notional | 969,311 | 973,331 |
| Credit default swaps | ||
| Derivative [Line Items] | ||
| Average Monthly Notional | 328,023 | 399,316 |
| Total return swaps | ||
| Derivative [Line Items] | ||
| Average Monthly Notional | 12,626 | 39,434 |
| Futures | ||
| Derivative [Line Items] | ||
| Average Monthly Notional | 110,200 | 167,708 |
| Options | ||
| Derivative [Line Items] | ||
| Average Monthly Notional | 4,876 | 19,825 |
| Forwards | ||
| Derivative [Line Items] | ||
| Average Monthly Notional | 35,847 | 30,930 |
| Warrants | ||
| Derivative [Line Items] | ||
| Average Monthly Notional | $ 1,538 | $ 2,222 |